(a) Field of the Invention
The present invention relates to a cover of a head up display and a housing that includes the cover. More particularly, the present invention relates to a cover of a head up display with an elliptic reflective surface and a housing that includes the cover.
(b) Description of the Related Art
In general, a head up display (HUD) has been developed to provide flight information to an airplane pilot and the HUD is mounted on an aircraft, particularly, a fighter. Recently, the HUD has been applied to a vehicle to conveniently report running information of the vehicle to a driver for the vehicle.
The HUD applied to the vehicle outputs various information such as running information or navigation information of the vehicle necessary to operate the vehicle and is mounted on a front glass window of the vehicle within a range without departing from a main visual field of a driver while the driver runs the vehicle.
The HUD for a vehicle as described above includes a liquid crystal panel installed an inner side of an instrument panel in front of a driver side to display a running information image, a light emitting unit or a backlight unit that illuminates the liquid crystal panel, an optical system that enlarges or reduces the running information image displayed on the liquid crystal panel to a suitable size and adjusts a focus of the image, and a reflecting mirror that reflects the running information image adjusted by the optical system on a front glass window of the vehicle to display the running information image on the front glass window of the vehicle.
The liquid crystal panel, the light emitting unit, the optical system, and the reflecting mirror are embedded and mounted within a housing that has a box shape. An opening that has a predetermined size is formed in the housing to allow image light reflected through the reflecting mirror to be irradiated to the front glass window of the vehicle. A dust cover or a cover is mounted in the opening to prevent a foreign material such as dust from flowing into the housing through the opening.
In the foregoing HUD for a vehicle, to enlarge a viewing region of the driver, the size of the opening must be increased. Due to limitation of a mounting space for the HUD and interference between peripheral components, the sizes of housing and the opening thereof may not be increased to a predetermined size or greater.
The above information disclosed in this section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.